Attempts to generate hydrogen have been extensively pursued by a large number of companies in all industrial countries, because hydrogen is considered by many to be the fuel of the future for its abundant occurrence in nature as water and the non-toxic by-product generated (water). Large quantities of hydrogen may be generated primarily from two sources: (1) from hydrocarbons and (2) water.
Generation of hydrogen from hydrocarbons, and/or methanol, is not green house gas-free as it produces carbon dioxide as byproduct. Of these two, only water, as the source of hydrogen, is pollution free. Generally, hydrogen generation from water is either by electrolysis or by water split reactions. Electrolysis involves use of electricity in splitting water. Pollution-free generation of electricity is only possible if renewable energy sources such as hydroelectricity, wind, solar, etc. are used. Even electric power generation using nuclear power station cannot be considered completely pollution-free.
For large scale commercialization of Proton Exchange Membrane (PEM) fuel cells, an easily available source of hydrogen gas is required. To meet this requirement i.e., hydrogen on demand several methods are currently employed such as, pressurized hydrogen gas or liquid in a tank or hydrogen stored chemically as a hydride or generation of hydrogen in situ by catalytic reforming of natural gas and/or methanol or other hydrocarbons. Hydrogen gas stored in a tank or as hydride obviously requires its generation from other sources.
Attempts to generate hydrogen from water on demand by water split reaction have been partly successful in some newer developments, which have been disclosed in recent patents (U.S. Pat. No. 6,440,385 B1, issued on Aug. 27, 2002 and U.S. Pat. No. 6,582,676 B2, issued on Jun. 24, 2003). In these patents aluminum was used to generate hydrogen from water, but is not very efficient, as this method requires large concentration of other materials in Al to accomplish the water split reaction.
There are several methods of generating hydrogen from water through chemical reaction described in the Patent literature, however, most of them suffer from cost and environmental problems (see U.S. Pat. No. 4,356,163; 5,514,353; 3,716,416 and 5,593,640).
There are a large number of patents for generating hydrogen from water using aluminum metal as the major consumable component. However, most of these involve other chemicals (activators) in the water to react with aluminum to generate hydrogen. The technology can be divided into several groups.                1. Al in water with NaOH and KOH        2. Alloying Al with other metals (including mechanical alloying) and then adding to water        3. Al with amalgam of Hg and other metals in water        4. Al in an aqueous electrolyte solution as an anode.        
In the prior art, all methods have some drawbacks such as use of environmentally unfriendly chemicals, high cost, no control over hydrogen generation rate, etc.
Various concepts have also been advanced on how to generate hydrogen from magnesium using an electrolyte, see for example
U.S. Pat. No. 6,113,806 dated Sep. 5, 2000 and U.S. Pat. No. 6,322,723 dated Nov. 27, 2001 both issued to Stephen R. Thomas describes the use of particulate metal compositions of magnesium with iron, aluminum and zinc added to water with alkali salt.
US 2004/0018145 A1 Patent dated Jan. 29, 2004—T. Suzuki et al., teaches the use of an aggregate consisting of Mg alloyed with Ni, Fe, V, Mn, Ti, Cu, Ag, Ca, Zn, Zr, or Al and other hydrogen generation material such as, NaH, Na, Ca, D, Sr, Li, or Be and hydrides with water. U.S. Pat. No. 3,957,483 dated 1976, also issued M. Suzuki, uses Mg composites having Fe, Zn, Cr, Al, and Mn added to water.
JP Patent #2003212501 A2 dated Jun. 30 2003—K. Izuru et al., teaches the use of aggregates formed from magnesium grains and catalyst metal particulates which are added to water to generate hydrogen. Metal particulates include Ni, Ni alloy, Fe, Fe alloy, V, V alloy etc.
The concept of generating hydrogen electrochemically is well known and has been described in the literature. U.S. Pat. No. 3,648,668 Mar. 14, 1972 to Pacheco teaches the generation of hydrogen using a magnesium (Mg) electrode and a carbon electrode in sea water or a salt solution and controlling production by a potentiometer which in turn is controlled by pressure sensor that senses the pressure of the produced and stored hydrogen gas.
U.S. Pat. No. 3,892,653 dated July, 1975; to F. Pacheco, teaches the use of magnesium as an anode, stainless steel as cathode; and sea water as electrolyte. The electrolyte is circulated. No electric current used but electric power generated in the system was used for electrolyzing water
U.S. Pat. No. 5,089,107 dated Feb. 18, 1992, F. Pacheco, describes an autoelectrolytic hydrogen generator system constituted by one or a plurality of similar cells wherein a galvanic arrangement of magnesium and aluminum plates of sacrificial elements as anode; stainless steel as cathode and sea water as electrolyte was used. When connected in short circuit causing a current to flow within the system and hydrogen production in situ commenced. Surplus electric energy of the system applied to an optional electrolyzer.
U.S. Pat. No. 4,340,580 dated Jul. 20, 1982, M. Suzuki, teaches generation of hydrogen using a Magnesium (Mg) electrode and another electrode in an electrolyte solution. An a.c. and d.c. voltage was applied.
U.S. Pat. Nos. 3,036,141 and 3,036,142 dated May 22, 1962 Goldenberg, describe magnesium galvanic cells comprising a magnesium or magnesium alloy anode, an aqueous electrolyte, and an inert cathode (steel or chrome plated steel) that were used to generate hydrogen (H2). The hydrogen produce was used to agitate the electrolyte
U.S. Pat. No. 3,256,504 dated Jun. 14, 1966 Fidelman, describes the production of hydrogen by reacting magnesium with water, the reaction being accomplished by galvanically coupling Mg with an active inert metal cathode in saline water.
WO 95/03637 Int. Publ date Feb. 2, 1995, S. Rosner, provides flow sheets and designed reactors (Fuel Cells) to generate hydrogen gas using a large number of previous patents.
US Patent Publ. #2004/0009392 A1 Publ. Date Jan. 15, 2004, P. J. Petillo and S. C. Petillo, teaches a Hydrogen generator that includes (a) an anode material (b) a cathode material and (c) an electrolyte; wherein the electrolyte comprises a metal hydride.
JP Patent #57191203 A2 dated Nov. 25, 1982, M. Suzuki, describes Mg being activated by contacting or electrically connecting with electroconductive matter and soaked in neutral aqueous electrolyte, esp. sea water. Thus, a 10 g Mg plate was rubbed with powder CuCl and soaked in 20% NaCl to generate hydrogen.
“Cathodic dissolution behaviour or an aluminum wire electrode in solution containing borate and sulfate ions” by Azumi et al. in the Journal of Electroanalytical Chemistry 567 (2004) 1-7 reports on the action on aluminum resulting in the evolution of hydrogen and the formation Al(OH)4.
Aluminum has a tendency to be self protecting by forming an oxide that inhibits reactions required for the formation of hydrogen and thus in some cases is difficult, if not, impossible to use on an extended term basis.
Obviously much work has been done to develop hydrogen generation processes to provide hydrogen for a variety of different purposes including power generation by combustion. Some provide control systems and teach production of hydrogen on demand, however the rate of production from these processes is not always up to the required rate without providing a production unit of undue size.